Space exploration is limited by a number of factors that prohibit the distance to which space vehicles can travel from the earth to the rest of the solar system. One obvious limitation is the size of a payload that can be placed into earth orbit and beyond. Tremendous power and fuel requirements are required to place larger payloads into earth orbit, and to then project those payloads to other locations in the solar system, such as the moon or Mars. The proposed NASA Ares-5 rocket is capable of delivering approximately 69 tons to earth escape velocity. However, NASA's current architecture requires a minimum of 77 tons to complete a crewed lunar mission that includes travel to and from the moon back to earth. Design changes for existing rockets can be achieved, but not without great additional expense. Increasing the payload capacity of existing launch vehicles is required for extended space exploration to locations such as Mars missions.
One alternative for satisfying mission performance needs for extended space exploration contemplates the use of an on-orbit fueling station, that reduces the Earth to orbit launch vehicle performance requirements down to the capability of existing booster rockets, and also enables great flexibility in attending to the different types of space missions in the expanding space industry. Providing an orbital refueling station has been contemplated with some prior designs, such as by NASA and Boeing. These prior designs typically are large space “gas stations” storing both oxidizer (typically LO2) and fuel (typically LH2) requiring on orbit assembly of elements launched by numerous launch vehicles. These large space stations also typically rely on zero-gravity cryo fluid management requiring significant additional development. However, a need still exists for providing an orbiting propellant depot using existing or near term technology that can be easily integrated within existing payload fairings, is economically feasible, and provides a reliable design that minimizes potential failure modes based upon the duration of time in which the propellant depot would be operating in space.